/*
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
package net.sf.l2j.gameserver.idfactory;

import java.util.BitSet;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Logger;

import net.sf.l2j.gameserver.ThreadPoolManager;
import net.sf.l2j.util.PrimeFinder;

/**
 * This class ..
 * 
 * @version $Revision: 1.2 $ $Date: 2004/06/27 08:12:59 $
 */
public class BitSetIDFactory extends IdFactory
{
    private static Logger _log = Logger.getLogger(BitSetIDFactory.class.getName());
    
    private BitSet          freeIds;
    private AtomicInteger   freeIdCount;
    private AtomicInteger   nextFreeId;
    
    public class BitSetCapacityCheck implements Runnable
    {

        /* (non-Javadoc)
         * @see java.lang.Runnable#run()
         */
        @Override
		public void run()
        {
            if (reachingBitSetCapacity())
            {
                increaseBitSetCapacity();
            }
        }
        
    }
    
    protected BitSetIDFactory()
    {
        super();
        ThreadPoolManager.getInstance().scheduleGeneralAtFixedRate(new BitSetCapacityCheck(), 30000, 30000);
        initialize();
        _log.info("IDFactory: "+ freeIds.size() + " id's available.");
    }
    
    public synchronized void initialize()
    {
        try
        {
            freeIds     = new BitSet(PrimeFinder.nextPrime(100000));
            freeIds.clear();
            freeIdCount = new AtomicInteger(FREE_OBJECT_ID_SIZE);
            
            for (int usedObjectId : extractUsedObjectIDTable())
            {
                int objectID = usedObjectId - FIRST_OID;
                if (objectID < 0)
                {
                    _log.warning("Object ID " + usedObjectId + " in DB is less than minimum ID of " + FIRST_OID);
                    continue;
                }
                freeIds.set(usedObjectId - FIRST_OID);
                freeIdCount.decrementAndGet();
            }
            
            nextFreeId  = new AtomicInteger(freeIds.nextClearBit(0));
        }
        catch (Exception e)
        {
            _log.severe("BitSet ID Factory could not be initialized correctly.");
            e.printStackTrace();
        }
    }
    
    @Override
	public synchronized void releaseId(int objectID)
    {
        if ((objectID - FIRST_OID) > -1)
        {
            freeIds.clear(objectID - FIRST_OID);
            freeIdCount.incrementAndGet();
        } else
            _log.warning("BitSet ID Factory: release objectID "+objectID+" failed (< "+FIRST_OID+")");
    }
    
    @Override
	public synchronized int getNextId()
    {
        int newID = nextFreeId.get();
        freeIds.set(newID);
        freeIdCount.decrementAndGet();
        
        int nextFree = freeIds.nextClearBit(newID);
        
        if (nextFree < 0)
        {
            nextFree = freeIds.nextClearBit(0);
        }
        if (nextFree < 0)
        {
            if (freeIds.size() < FREE_OBJECT_ID_SIZE)
            {
                increaseBitSetCapacity();
            }
            else
            {
                throw new NullPointerException("Ran out of valid Id's.");
            }
        }

        nextFreeId.set(nextFree);

        return newID + FIRST_OID;
    }
    
    @Override
	public synchronized int size()
    {
        return freeIdCount.get();
    }
    
    protected synchronized int usedIdCount()
    {
        return (size() - FIRST_OID);
    }
    
    protected synchronized boolean reachingBitSetCapacity()
    {
        return PrimeFinder.nextPrime(usedIdCount() * 11 / 10) > freeIds.size();
    }
    
    protected synchronized void increaseBitSetCapacity()
    {
        BitSet newBitSet    = new BitSet(PrimeFinder.nextPrime(usedIdCount() * 11 / 10));
        newBitSet.or(freeIds);
        freeIds             = newBitSet;
    }
}